1. Field of the Invention
The present invention relates to a high-voltage component, more particularly, to a high-voltage metal-oxide-semiconductor (HVMOS) transistor.
2. Description of the Prior Art
High-voltage components are generally used in power circuits of flat panels or flash memory, having particular structures for sustaining high voltages, wherein the HVMOS transistors may function as switches and are broadly utilized in central processing unit (CPU) power supplies, power management systems, AC/DC converters, liquid crystal display (LCD) and plasma TV drivers, automobile electronic components, personal computer (PC) peripheral devices, small DC motor controllers, and other consumer electronic devices.
Generally, an oxide layer is formed between the gate electrode, and the source and drain electrodes in the HVMOS transistor to reduce the vertical electric field in the channel. However, with the progress of semiconductor and the trend towards scaling down the size of the semiconductor devices nowadays, the thicknesses of the oxide layer have to be decreased accordingly, thereby resulting in severe band-to-band tunneling effect and gate induced drain leakage (GIDL). Thus, the quality and reliability of electronic devices are seriously affected.
All the way through, the leakage current and reduced breakdown voltage is one of the key issues to impact the reliability of miniaturized semiconductor devices. Especially when the sizes of the semiconductor devices are minimized, the problem caused by the leakage current will become increasingly severe. Therefore, there is an urgent need of overcoming disadvantages of conventional HVMOS transistors, such as the gate induced drain leakage and other issues, in order to meet the practical requirement.